1. Field of the Invention
The invention relates to techniques for determining formation fluid properties. More particularly, the invention relates to determining the composition of fluid in a pressure compartment in order to develop a drilling plan for a reservoir.
2. Background of the Related Art
The oil and gas industry has traditionally classified reservoirs by structures subdivided into geological units or pressure compartments in order to characterize fluids in a formation. During the exploration cycle of the process, the resolution may be improved from seismic/aero magnetic surveys to wireline logs, and the pressure compartments may be further subdivided based on higher resolution log responses from gamma ray (GR), nuclear density, resistivity and nuclear magnetic resonance logs (NMR). The log responses are based on well known physics in the domains, and log/tool readings are affected by lithological changes and rock fluid content.
With the emergence of near infra red (NIR) analysis, there is now capability to physically measuring critical fluid properties of formation fluid which may be produced through a wireline formation tester (WFT) tool by using a pump. As a result, it has been determined that pressure compartments typically do not contain one type of fluid but instead, the fluid has considerable variation which shows either completely different fluids or a fluid compositional gradient in the compartments.
Despite the development and advancement of various methods for determining formation fluid properties based on acquiring formation fluid samples from inside the wellbore, there remains a need to provide techniques capable of determining the composition of fluids in pressure compartments and incorporating fluid characteristics in the geophysics and geology cycle.